proteinemia

Generality

Proteinmia is a blood chemistry parameter aimed at quantifying the total proteins present in the blood.

Normally, an adult in good health has a proteinemia of about 7 grams per deciliter of plasma (reference values 6.4 - 8.3 g / dL).

What's this

Proteinmia indicates the total amount of the various types of proteins present in the liquid part (plasma) of the blood.
The concentration of proteins in the blood is usually relatively stable, as it reflects a balance between the loss of old molecules and the production of new ones.
Albumin and globulin together account for about 95% of circulating plasma proteins, which together make up about 7% of the blood.

Proteinemia: biological meaning

The blood is ideally formed by two components: a liquid fraction - which takes up just over 50% of its volume - and a cellular component (red blood cells, white blood cells and platelets).

The liquid fraction of the blood is called plasma and is formed by inorganic salts, proteins, gases, organic constituents and above all by water. Also this blood component, like the cellular one, covers important and essential functions for life. In particular, the biological role of plasma proteins can be summarized as follows:

Regulation of colloidosmotic pressure;
Transport function (transferrin, ceruloplasmin, haptoglobin, hemopexin);
Buffer function (acid-base balance);
Defensive function (blood coagulation, immunity and inflammatory response);
Regulation of numerous activities of the organism (among the plasma proteins also the peptide hormones are included).

Why do you measure

Proteinmia is an examination that serves to quantify the proteins present in the blood. Often, this parameter is measured as part of the analysis panel performed during routine checks, so it is frequently used in assessing a person's general health status.

The concentration of proteins in the blood can provide general information about nutritional status, useful, in particular, when the patient has inexplicably lost weight.

Proteinemia can be prescribed together with other tests to understand the cause of an abnormal accumulation of fluid in the tissues (edema) and as a support to the diagnosis of some liver and kidney diseases.

When is the exam prescribed?

The doctor may prescribe the examination as part of a general check-up or to investigate the origin of suspicious symptoms for liver, kidney or bone marrow disorders, such as:

Weight loss for no apparent reason;
Fatigue;
Jaundice (yellowish color of the skin);
Edemas (swellings);
Swelling around the eyes, stomach or legs (signs of nephrotic syndrome).

Normal values

The reference range for the protehemia is between 6.4 and 8.3 g / dL.

High Proteinemia - Causes

Protein can increase compared to values considered normal in the presence of:

Excessive synthesis of proteins by the liver (haemoconcentration, some autoimmune diseases, etc.);
Dehydration;
Bone marrow disorders, such as multiple myeloma;
Venous stasis during collection.

A high concentration of protein in the blood (hyperproteinemia) can also be observed in chronic inflammatory diseases and infections, such as viral hepatitis or HIV.

Low Proteinemia - Causes

A low concentration of protein in the blood (hypoproteinemia) may suggest the presence of various diseases.

In particular, the protein can decrease in the following conditions:

Reduced hepatic function, that is the liver is not able to synthesize sufficient proteins for the regular functioning of the organism;
Decreased synthesis caused by insufficient dietary intake or compromised absorption of proteins, as happens in malnutrition and in severe liver diseases. Low concentrations can also be observed in celiac disease or in inflammatory bowel diseases;
Excessive catabolism or loss of proteins from the kidney or intestine, as may occur during renal diseases (nephrotic syndrome);
Increased volume (as in the case, for example, of congestive heart failure).

Low protein levels may also depend on overhydration, bleeding and burns.

How to measure it

Protein examination is performed on a blood sample taken from a vein in the arm or collected by puncture of the finger (children and adults) or heel (newborns).

Preparation

For the evaluation of proteins in the blood, it is necessary to be fasting for 8-10 hours.

Prolonged application of the tourniquet during blood sample collection can lead to a false rise in the protehemia (greater than the actual quantity of circulating proteins).

The drugs that can influence the outcome of the analysis, reducing the measured value, are estrogens and oral contraceptives.

Interpretation of Results

The results of the proteins are considered together with those of other analyzes and provide the doctor with information on the general state of health of the patient.

If the result is abnormal, it is advisable to undergo further tests to identify the pathological condition that affects the concentration of protein in the blood.

High or low proteinemia: physio-pathological meaning

Plasma proteins are synthesized in the liver, except for the γ-globulin (produced by activated lymphocytes), hormones and some enzymes.

The catabolism of plasma proteins occurs instead at the level of the intestinal mucosa and of the capillary endothelium, while normally there are no significant losses at the urinary level.

As mentioned, the protehemia represents an important index of liver function; in fact, faced with the finding of low concentrations of plasma proteins (hypoproteinemia), the first thought goes to the liver, which could be unable to synthesize them in adequate quantities (liver failure). However, the causes of hypoproteinemia do not always reside in the liver; the origin of this condition may indeed be:

Hyperhydration, with increase in volume (proportional reduction of all fractions)
Decreased synthesis due to insufficient food intake. Eg: for malabsorption, for chronic liver diseases, malnutrition, severe immunodeficiencies, etc.
Protein loss from kidney (nephrotic syndrome), from the intestine, from bleeding, from neoplasms, from burns, etc.
Excessive endogenous protein catabolism (burns, hyperthyroidism, neoplasms, overtraining).

The opposite situations are more rare, characterized by an increase in the protemiamia ( hyperproteinemia ).

Possible predisposing factors include:

For dehydration, haemoconcentration, venous stasis during collection (proportional increase of all fractions).
Increased gamma-globulin (despite the drop in albumin) in some situations of liver cirrhosis, autoimmune diseases etc.
Presence of abnormal proteins (polyclonal or monoclonal gammopathies) etc.

In the face of altered proteins it is important to assess whether the alteration affects all protein fractions or only some of them.

Plasma protein reference values	Possible causes of low values	Possible causes of high values
Albumin: 3.5-5.0 gr / dl	Prolonged fasting, low-protein diet, vomiting, diarrhea, kidney or liver disease, febrile illness	Dehydration or vomiting
Alpha 1 globulin: 0.1-0.3 gr / dl	Pulmonary emphysema, liver disease, kidney disease (nephrotic syndrome), alpha-1 antitrypsin deficiency, scleroderma	Taking oral contraceptives, infectious diseases or chronic inflammatory diseases, such as systemic lupus erythematosus and rheumatoid arthritis, myocardial infarction or neoplasms
Alpha 2 globulins: 0.6-0.1 gr / dl	Joint inflammation, viral hepatitis, pancreatitis, hemolysis	Acute bacterial infections, trauma, surgery, renal and liver malfunction, diabetes, acute and chronic inflammation
Beta globulins: 0.7-1.2 gr / dl	Congenital diseases that cause protein deficiency or malfunction of the stomach or intestines, congenital coagulation disorders, disseminated intravascular coagulation	Pregnancy, liver cirrhosis, renal function abnormalities, estrogen therapy, hyperlipoproteinemia (eg familial hypercholesterolemia)
Gamma globulins: 0.7-1.6 gr / dl.	Malnutrition, kidney damage, burns, use of immunosuppressive drugs	Chronic autoimmune hepatitis, acute viral hepatitis, liver cirrhosis, acute and chronic bacterial infections, drug intake, multiple myeloma, chronic liver disease, chronic inflammatory diseases

NOTE: the reference values for the protehemia and the other blood chemistry parameters may vary slightly from laboratory to laboratory. For this reason, it is preferable to consult the ranges listed directly on the report. It should also be remembered that the results of the analyzes must be assessed as a whole by the general practitioner who knows the patient's medical history.